A lithium secondary battery produces electric energy through oxidation/reduction reaction in intercalation/deintercalation of lithium ions in and from the positive electrode and the negative electrode thereof. The lithium secondary battery uses a substance enabling reversible intercalation/deintercalation of lithium ions as the active material of the positive electrode and the negative electrode thereof, in which an organic electrolytic solution or a polymer electrolyte is filled between the positive electrode and the negative electrode.
Lithium secondary batteries have become widely used as power supplies for mobile telephones and mobile electronic appliances, as having a high energy density and lightweight as compared with conventional secondary batteries. In those days when lithium secondary batteries were first put on the market, there were various problems of insufficient battery capacity, insufficient charge-discharge cycle property and insufficient large-current load property. Afterwards, improvement of battery-constitutive materials has promoted considerable improvement of battery characteristics, therefore supporting the high performance of recent mobile electronic appliances. Nowadays, application of lithium secondary batteries to electric power tools, electric vehicles and others that especially require a large-current load property has been promoted. Further, investigation of lithium secondary batteries as power sources for vehicles and heavy machinery is actively made. In these use applications, the batteries are required to have charge characteristics along with discharge characteristics, or that is, the ability of rapid charging within a short period of time.
In that situation, in Patent Reference 1 (JP-A 2005-135905), heat treatment of a readily-graphitizable carbon material at 1700 to 2500° C. is investigated. Patent Reference 2 (JP-A 2007-19257) discloses a carbon material prepared through heat treatment of a petroleum or coal coke at a relatively low temperature of from 600 to 1400° C., as an electrode material.